There has been a steering device for a vehicle for conducting steering of wheels of an automobile or the like, which includes a column shaft to which a steering wheel is mounted, a steering shaft for steering the wheels for steering by way of a steering mechanism such as a steering gear box, and a cross shaft joint for tiltably coupling the column shaft and the steering shaft to each other.
The cross shaft joint which is used in the steering device for a vehicle includes a cross shaft having four shaft parts which are protruded from side peripheral faces of a body part thereof in four directions in a shape of a cross, a plurality of needle rollers rolling on outer peripheral faces of the shaft parts, and bearing cups having a bottomed cylindrical shape which are externally fitted to these needle rollers. The bearing cups are inserted into bearing holes in yokes which are respectively provided in the column shaft and the steering shaft, thereby allowing the shaft parts to rotate with respect to the yokes. By coupling the yokes of the two shafts to each other byway of the cross shaft, as described above, this cross shaft joint tiltably couples the two shafts.
In the cross shaft joint as described above, it has happened, in some cases, that when a transmitted torque grows larger, slips occur in the needle rollers, and faulty torque transmission such as backlashes, pulsations occurs, which badly affects steering feeling of the relevant steering device for a vehicle. In view of the above, there is disclosed, in the below mentioned Patent Document 1, an art that each of the bearing cups is provided with a curved part which is curved to project radially inward, in a center part in an axial direction of the cylindrical part thereof, and each of the needle rollers is elastically pressed radially inward by this curved part so that the needle roller is maintained in tight fit state (state of a negative gap) with respect to the shaft part.